Fuel cells have been extensively studied for numerous applications, including automotive applications. A key component of a fuel cell is the electrocatalyst, the nature of which will impact on both performance and cost of the fuel cell. A typical electrocatalyst is formed from platinum particles on a carbon support. There is often an aggregation problem for the platinum particles on the carbon support under fuel cell conditions, and this reduces the efficiency of the electrocatalyst and requires more platinum than would be otherwise necessary. Catalyst utilization is also reduced by the presence of large particles. The tremendous demand for platinum has greatly increased its cost. Reducing the amount of platinum used in a fuel cell would greatly aid commercialization of this technology.
In a typical polymer electrolyte membrane (PEM) fuel cell (FC), the PEM is sandwiched between two electrodes, an anode and a cathode. The fuel cell includes a supply of fuel such as hydrogen gas to the anode, where the hydrogen is converted to hydrogen ions (protons) and electrons. Oxygen is supplied to the cathode, where the oxygen, hydrogen ions conducted through the PEM, and electrons conducted through an external circuit combine to form water. Electrocatalysts are used to facilitate these electrode reactions. For better fuel cell performance, the catalytically active material (platinum) should be in contact with an electron-conducting material such as carbon black that conducts the electrons, and a proton conductor (the PEM) that conducts the protons. However, in a conventional PEM fuel cell, if platinum is located in pores of the carbon black, contact with the PEM may be lost, reducing effectiveness.